Fabrication of a super-hydrophobic nanofibrous zinc oxide film surface by electrospinning

We report a new approach for fabricating a super-hydrophobic nanofibrous zinc oxide (ZnO) film surface. The pure poly(vinyl alcohol) (PVA) and composite PVA/ZnO nanofibrous films can be obtained by electrospinning the PVA and PVA/zinc acetate solutions, respectively. After the calcination of composite fibrous films, the inorganic fibrous ZnO films with a reduced fiber diameter were fabricated. The wettability of three kinds of fibrous film surfaces were modified with a simple coating of fluoroalkylsilane (FAS) in hexane. The resultant samples were characterized by field emission scanning electron microscopy (FE-SEM), water contact angle (WCA), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). It was found that the pure PVA fibrous films maintained the super-hydrophilic surface property even after the FAS modification. Additionally, the WCA of composite fibrous films was increased from 105 to 132° with the coating of FAS. Furthermore, the surface property of inorganic ZnO fibrous films was converted from super-hydrophilic (WCA of 0°) to super-hydrophobic (WCA of 165°) after the surface modification with FAS. Observed from XPS data, the hydrophobicity of FAS coated various film surfaces were found to be strongly affected by the ratio of fluoro:oxygen on the film surfaces.     

Control of spatial polarization by use of a liquid crystal with an optically treated alignment layer and its application to beam apodization

We have investigated the alignment of a liquid crystal whose orientation is controlled by photoisomerization reaction for use in developing optical devices to improve beam quality. A glass window of a liquid-crystal cell that is coated with poly(vinyl alcohol) doped with azo dye was illuminated with a Hg lamp. We confirmed the dependence of the spatially controlled alignment direction of a liquid crystal on the irradiation time of this ultraviolet light. The new azo dye used in this study substantially reduced the illumination energy density required for aligning liquid-crystal molecules. We have demonstrated the control of polarization and successfully fabricated a serrated apodizing aperture and a soft aperture.     

Electrical resistivity of porous carbon materials, “Woodceramics” at low temperatures

Woodceramics obtained by carbonizing woody materials are new carbon materials recently developed for industrial use. They are porous, light, hard and cheap to produce and have heat and corrosion resistance. They are being considered for applications in various fields. We investigated the dependence of the electrical resistivity of Woodceramics at temperatures between 100 K and 300 K, and considered the conduction mechanism of Woodceramics which are porous conductors. The electrical resistivity of Woodceramics decreases as sintering temperature increases. It varies over a wide range. And the resistivity dependence on the temperature of Woodceramics is similar to that of a semiconductor. We propose that the semiconducting behavior is caused by an energy gap decrease which depends on the sintering temperature, as a result of change in size of the graphite micro-crystallites in glassy carbon which is present in Woodceramics.     

Increased impact strength of biodegradable poly(lactic acid)/poly(butylene succinate) blend composites by using isocyanate as a reactive processing agent

Poly(lactic acid) (PLA) blended with poly(butylene succinate) (PBS) was prepared in the presence of lysine triisocyanate (LTI) by using a twin‐screw extruder and injection molding machine. The physical properties, rheological behavior, compatibility, and morphology were investigated by using a tensile test, a Charpy impact test, melt mass‐flow rate (MFR) measurements, size exclusion chromatography (SEC), and laser scanning confocal microscopy (LSCM). The impact strength of PLA/PBS(90/10 wt %) blend composite was about 18 kJ/m² in the absence of LTI, and it increased to 50–70 kJ/m² in the presence of LTI at 0.5 wt %. The MFR value of PLA/PBS(90/10 wt %) decreased from 25 g/10 min at 200°C in the absence of LTI to approximately 3 g/10 min in the presence of LTI. These results imply that isocyanate groups of LTI reacted with both terminal hydroxyl or carboxyl groups of the polymers. Spherical particles at 1 μm were observed by using LSCM in the presence of LTI. These results indicate that the LTI is a useful reactive processing agent to increase the compatibility of PLA/PBS blend composites to increase the impact strength of PLA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Anion-exchange separation in hydrochloric acid solutions for the ultrahigh purification of cobalt

Recent application in advanced electronics have increased the practical importance of ultrahighpurity cobalt. Anion exchange in HCl media is considered an efficient alternative to the combination of the conventional purification methods. Anion-exchange distribution functions have been determined for cobalt and the main impurity elements by the technique of batch equilibration. Spectrophotometric and elution studies confirmed the established anion-exchange behavior patterns. Based on the new and the available distribution functions, combined with the assessment of thermodynamic stability, a procedure of anion-exchange separation has been devised to eliminate virtually all the impurities from the cobalt-chloride solution. The major shortcoming of previously proposed anion-exchange procedures—failing to separate copper sufficiently—has been corrected by the introduction of a preliminary step under reduced conditions, removing copper from the solution by sorption in the monovalent state. The rest of the impurities are eliminated in a second anion-exchange step by applying rinsing and elution stages under oxidizing conditions. The optimum parameters of the procedure have been determined according to performance characteristics (purification ratios, yields, and volume efficiencies) derived from the analysis of elution curves obtained with laboratory-scale ion-exchange columns. Special computer programs have been developed to facilitate thermodynamic simulation, analytical correction, and data processing.     

An image segmentation method using histograms and the human characteristics of HSI color space for a scene image

Image segmentation is an important subject for image recognition. Here, we propose a new image segmentation method for scene images. The proposed segmentation method classifies images into several segments based on the human visual sense and achromatic color. We calculate the histograms of the image for each component of the hue, saturation, and intensity (HSI) color space, and obtain three results of image segmentation from each histogram. We consider achromatic colors in order to decrease the number of regions. We compare the results of the proposed method with those of the k-means methods for the effectiveness of the proposed method. This work was presented, in part, at the 10th International Symposium on Artificial Life and Robotics, Oita, Japan, February 4–6, 2005     

Sol-gel PZT thin films on nickel alloy electrodes

Abstract

The Ni alloy electrode was used for a bottom electrode of PZT thin films prepared by sol-gel process. Although PZT films were crystallized on soda–lime glass substrates with the alloy electrodes at a relatively low temperature of 500°C, second phases of Pb₃O₄ and ZrTiO₄ were produced on the electrode in addition to the perovskite PZT phase. In order to prevent the second phases forming, the heat treatment time of the electrode was increased to obtain the thicker Al₂O₃ layer on the alloy electrode. The second phases decreased with increasing the heat treatment time; however, the phases did not disappear. When BaTiO₃ films were inserted between the electrodes and PZT films, the PZT single phase was obtained. The tan δ of the films decreased with decreasing the amount of the second phases, finally it became 3.9%, the film of which possessed a remanent polarization of 20 μC/cm².     

Fabrication of 1K-Bit 1T2C-Type Ferroelectric Memory Cell Array

A 1K-bit 1T2C-type ferroelectric memory array has been designed and fabricated by combination of a 0.35 μm gate length CMOS process and a 3 μm design rule ferroelectric process. The write and readout operation in a 1K-bit 1T2C-type memory array cell has been confirmed experimentally.     

Effects of Intermediates between Vitamins K(2) and K(3) on Mammalian DNA Polymerase Inhibition and Anti-Inflammatory Activity

Previously, we reported that vitamin K(3) (VK(3)), but not VK(1) or VK(2) (=MK-4), inhibits the activity of human DNA polymerase γ (pol γ). In this study, we chemically synthesized three intermediate compounds between VK(2) and VK(3), namely MK-3, MK-2 and MK-1, and investigated the inhibitory effects of all five compounds on the activity of mammalian pols. Among these compounds, MK-2 was the strongest inhibitor of mammalian pols α, κ and λ, which belong to the B, Y and X families of pols, respectively; whereas VK(3) was the strongest inhibitor of human pol γ, an A-family pol. MK-2 potently inhibited the activity of all animal species of pol tested, and its inhibitory effect on pol λ activity was the strongest with an IC(50) value of 24.6 μM. However, MK-2 did not affect the activity of plant or prokaryotic pols, or that of other DNA metabolic enzymes such as primase of pol α, RNA polymerase, polynucleotide kinase or deoxyribonuclease I. Because we previously found a positive relationship between pol λ inhibition and anti-inflammatory action, we examined whether these compounds could inhibit inflammatory responses. Among the five compounds tested, MK-2 caused the greatest reduction in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced acute inflammation in mouse ear. In addition, in a cell culture system using mouse macrophages, MK-2 displayed the strongest suppression of the production of tumor necrosis factor (TNF)-α induced by lipopolysaccharide (LPS). Moreover, MK-2 was found to inhibit the action of nuclear factor (NF)-κB. In an in vivo mouse model of LPS-evoked acute inflammation, intraperitoneal injection of MK-2 in mice led to suppression of TNF-α production in serum. In conclusion, this study has identified VK(2) and VK(3) intermediates, such as MK-2, that are promising anti-inflammatory candidates.